A variety of pressure vessels (including vacuum vessels) are known in the prior art which require a closure device for access. For example, such equipment includes gas filters, filter separators, gas scrubbers, pipeline scraper, launchers and receivers, meter provers, access openings to pressure vessels, liquid phase separators/coalescers, and the like. The equipment of the above type often features an ASME and/or API quick opening closure for access to the vessel or equipment interior.
For example, the examples of quick opening type closures therefore include U.S. Pat. No. 6,439,415 assigned to the present assignee, Perry Equipment Corporation and UK Patent No. GB 2172956. These patents show a closure for an equipment sub which includes a cylindrical aperture which is closed by a circular closure door member having an O ring seal.
The present invention pertains to improvements over the state of the art, including several different inventive aspects.